Some image display devices such as liquid crystal monitors and liquid crystal projectors are provided with a display panel having a plurality of pixels, scan these pixels in a predetermined scanning sequence, and draw images.
FIG. 1 is a schematic diagram showing the structure of the foregoing image display device. As shown in FIG. 1, the image display device has liquid crystal panel 101, horizontal drive circuit 102, sample hold circuit 103, and vertical drive circuit 104.
Liquid crystal panel 101 has a plurality of scanning lines SCN; a plurality of signal lines SIG that intersect with individual scanning lines SCN; and a plurality of pixels PX that are located respectively at intersections of individual scanning lines SCN and individual signal lines SIG. Each pixel PX is composed of a liquid crystal cell and is connected to scanning line SCN and signal line SIG through transistor TFT. More specifically, a gate electrode of transistor TFT is connected to scanning line SCN; a source electrode thereof is connected to signal line SIG; and a drain electrode thereof is connected to pixel PX.
Horizontal drive circuit 102 starts operating in synchronization with a horizontal synchronization signal for an image signal and outputs a sampling signal that causes the image signal to be sampled to sample hold circuit 103 in synchronization with an input clock signal.
Sample hold circuit 103 samples pixel values of individual scanning lines of the image signal in synchronization with the sampling signal that is input from horizontal drive circuit 102 and holds pixel values of one scanning line of the image signal. Thereafter, sample hold circuit 103 outputs pixel voltages corresponding to the pixel values that have been held to individual signal lines SIG.
Vertical drive circuit 104 applies the pixel voltages that are input from sample hold circuit 103 to pixels PX connected to individual scanning lines SCN so as to scan pixels PX of individual scanning lines SCN.
More specifically, vertical drive circuit 104 outputs vertical scanning timing pulses that cause transistors TFT to be turned on to individual scanning lines SCN in a predetermined sequence at timings corresponding to the horizontal synchronization signal and vertical synchronization signal for the image signal, turns on transistors TFT connected to individual scanning lines SCN, and thereby applies the pixel voltages to individual pixels PX.
FIG. 2 is a timing chart showing timings at which the vertical scanning timing pulses are output. FIG. 3 is a schematic diagram showing a horizontal scanning sequence in which scanning lines SCN are scanned corresponding to the vertical scanning timing pulses. In FIG. 2 and FIG. 3, it is assumed that the number of scanning lines SCN is n and they are assigned scanning line numbers 1 to n that are in sequence from top to bottom on liquid crystal panel 101.
As shown in FIG. 2 and FIG. 3, vertical drive circuit 104 starts operating in synchronization with the vertical synchronization signal and outputs vertical scanning timing pulses to individual scanning lines SCN that are in sequence from top to bottom on liquid crystal panel 101 in synchronization with the horizontal synchronization signal. As a result, individual pixels PX are successively scanned corresponding to individual scanning lines SCN that are in sequence from top to bottom on liquid crystal panel 101.
In the image display device provided with liquid crystal panel 101, liquid crystal cells do not quickly respond to pixel voltages. In addition, a display image remains displayed for one frame period of the image signal. Thus, when a moving image is displayed, an afterimage of each frame of the image signal and the image of the next frame are mixed with each other and thereby a so-called moving blur where the viewer sees a blurred image may occur.
In contrast, Patent Literature 1 describes an image processing device that can eliminate a moving blur.
The image processing device described in Patent Literature 1 detects the position of an object that is moving in a display image and the amount of that the object has moved based on two successive frames of an image signal and corrects the image signal based on the detected result so as to eliminate the moving blur. More specifically, the image processing device adds a correction values to pixel values of pixels located between the position before the object is moved and the position after it is moved so as to offset the afterimage and thereby eliminate the moving blur.